Dive Theory: lung overexpansion explained

Lung overexpansion injuries fall under the category of Decompression Illness. Unlike decompression sickness (which also falls under this category), lung overexpansion injuries are a type of barotrauma caused by ascending improperly. If a diver holds their breath while ascending, the air in their lungs expands as the pressure decreases and can cause damage, leading to potential medical emergencies. There are four types of lung overexpansion injuries, which we explain in lovely simple terms below!

AGE - Arterial Gas Embolism

A bubble of gas in an artery

Translation: Arterial (occurring in the artery); Gas (air); Embolism (a mass or obstruction) so... a bubble of air in a blood vessel.

What it is: A bubble of gas forms in an artery. As blood is pumped around the body, this bubble will travel through the blood vessels, and can either end up in the heart, which can cause a heart attack, the brain, which can cause a stroke, or the lungs, which can cause a pulmonary embolism.

Signs & Symptoms:

• Difficulty breathing

• Loss of Consciousness

• Altered mental state/confusion

• Weakness or paralysis (if entered the brain)

• Pink frothy sputum (if entered the lung)

• Chest pain (if entered the heart)

Seriousness scale: VERY - seek emergency medical services

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Pneumothorax

Air between the lung and chest wall

Translation: Pneumo (referring to air); thorax (referring to the chest) so... air in the plural space causing a squashed (collapsed) lung.

What it is: Imagine each lung as a large flexible sack, and imagine this sack sits surrounded by an inflexible wall. In a pneumothorax, air gathers in the space between the wall and the sack (known as the pleural space). This mass of air forces the sack into a smaller area. The more air that enters this space, the smaller the sack will be squashed.

Signs & Symptoms

•    Difficulty Breathing

•    Shortness of Breath (SOB)

•    Sudden or sharp pain in the chest area (usually one sided)

Seriousness Scale: Mild to moderate (depending on the size of the pneumothorax)

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Mediastinal Emphysema

Air bubbles around the chest area

Translation: media (middle) sternum (chest) so mediastinal (referring to the central part of the chest); emphysema (from the Greek word meaning to inflate or in medical terms, abnormal presence of air in the tissues) so... bubbles of air around the chest

What it is: Small gas bubbles come out of the tissues and gather around the central chest area, in the space between the lungs and the heart. This can cause a tightness in the chest and could lead to, or follow a pneumothorax.

Signs & Symptoms

• Centralised chest pain

• Shortness of breath

Seriousness Scale: Mild to moderate - but monitor for deterioration

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Subcutaneous Emphysema

Air bubbles under the skin

Translation: Sub (under); cutaneous (referring to the skin); emphysema (presence of air in tissues)so... bubbles of air under the skin

What it is: Small gas bubbles form and gather just under the skin. This is usually develops around the neck area, but could form anywhere, and can be felt when touched - feels like bubble wrap or rice krispies (actually called crepitus).

Signs & Symptoms

• Potential pain around the affected area

• Difficulty breathing

• The feel of crackling on touch (crepitus)

• Swelling around the neck

• Possibly difficulty swallowing or speaking

Seriousness Scale: Mild - but monitor for deterioration, especially the airway

No matter which one, the first aid is always to provide oxygen, seek medical care and monitor for deterioration!